In 1984, the company Uhde entertained business relations with various cities in the People's Republic of China, including Xi'an. A delegation from the Shaanxi province came to visit the company Uhde. The University of Dortmund already established contact with the University of Xian Jiaotong in 1985.
In February 1986, the chief municipal director, Harald Heinze, informed the Council of the Elderly that several Chinese cities had expressed an interest in initiating twinning relations with Dortmund. After further investigations and discussions, Xi'an was proposed as a twin city, because of its good infrastructure (airport), its industries, which were of interest to Dortmund's companies, and because contact had already been established with its University. One hoped that this would have a positive effect on the economy.
In May 1986, the City of Dortmund informed the City of Xi'an that they would be very interested in initiating twinning relations and invited Xi'an's Lord Mayor and a delegation to visit Dortmund. In return, Xi'an's Director of Foreign Affairs sent a letter to the representatives of Dortmund on September 19, 1986, inviting them to visit Xi'an. As the letter stated, this was to clear formalities, to organise exchanges and further cooperation, and to awaken mutual sympathy and friendship (for instance, through student exchanges, the exchange of expertise, as well as artistic exchanges and organising events and exhibitions).
Following this invitation, a delegation of 11, headed by the chief municipal director, visited Xi'an. On April 10, 1987, a comprehensive declaration of intent was signed by both cities, which detailed the possibilities and the form in which cooperation would take place in future:
"Both parties are committed to furthering the continuous development of friendly cooperation between Xi'an and Dortmund..."
Various encounters follow: RWAG (now known as the Foreign Association), for instance, organises a "China Week", Dortmund's Actien Brewery shares its know-how with a brewery in Xi'an that is still under construction, work and contact trips are organised by the University of Dortmund, student exchanges take place, a group of journalists from Xi'an visit Dortmund, etc.
From June 24 to July 5, 1988, an official delegation of six are invited to be guests at City of Dortmund. A joint declaration is signed by Dortmund's Lord Mayor and the Chairman of the Provincial People's Congress. The City of Dortmund expresses its interest in organising a one-to-one terracotta exhibition and preparations for this begin.
The People's Congress of the City of Xi'an decide to enter into a twinning relationship with Dortmund on March 1, 1989. In Dortmund, no decision regarding this has yet been made.
After the brutal suppression of the Student's and People's Democratic Movement on the Tiananamen Square in Bejing in early June 1989, the Council of Dortmund makes the following written statement on June 15:
"The events in China fill us with grief and horror. The fractions of the Council reinforce their wish to enter into a partnership with the City of Xi'an. However, they also agree that they are not able to reach a decision about this at this point in time."
The preparations for the Terracotta exhibition continue, resulting in the display of original exhibits from Xi'an's terracotta army in the Museum am Ostwall in Dortmund from August 12 to November 11, 1990.
On June 27, 1991, the Council of Dortmund does eventually pass a resolution to initiate a twinning relationship with Xi'an.
On July 22, 1992, the Lord Mayor of Xi'an Ciu Lintao and Dortmund's Lord Mayor Günter Samtlebe officially signed the charter of friendship:
"Both parties are in agreement that they will apply the principle of equal rights and make reciprocal use of the close ties they have developed. For this reason, they will amicably and by mutual agreement further and develop in a variety of ways the exchange of expertise and cooperation in the fields of business, science, technology, culture, education, sports, as well as other areas of common interest, in the interests of both cities."